As the semiconductor processing industry strives for larger production yields while increasing the number of circuits per unit area, attention has been focused on the continued development of reliable high-resolution patterning techniques. One such technique in use today is commonly referred to as imprint lithography. Imprint lithography processes are described in detail in numerous publications, such as U.S. Patent Application Publication No. 2004/0065252, and U.S. Pat. Nos. 6,936,194 and 8,349,241, all of which are incorporated by reference herein. Other areas of development in which imprint lithography has been employed include biotechnology, optical technology, and mechanical systems.
An imprint lithography technique disclosed in each of the aforementioned patent documents includes formation of a relief pattern in an imprint resist and transferring a pattern corresponding to the relief pattern into an underlying substrate. The patterning process uses a template spaced apart from the substrate and a polymerizable composition (an “imprint resist”) disposed between the template and the substrate. In some cases, the imprint resist is disposed on the substrate in the form of discrete, spaced-apart drops. The drops are allowed to spread before the imprint resist is contacted with the template. After the imprint resist is contacted with the template, the resist is allowed to uniformly fill the space between the substrate and the template, then the imprint resist is solidified to form a layer that has a pattern conforming to a shape of the surface of the template. After solidification, the template is separated from the patterned layer such that the template and the substrate are spaced apart.
Throughput in an imprint lithography process generally depends on a variety of factors. When the imprint resist is disposed on the substrate in the form of discrete, spaced-apart drops, throughput depends at least in part on the efficiency and uniformity of spreading of the drops on the substrate. Spreading of the imprint resist may be inhibited by factors such as gas voids between the drops and incomplete wetting of the substrate and/or the template by the drops. Spreading of the imprint resist may be facilitated by pretreating the substrate with a composition having a higher surface tension than that of the imprint resist. However, the difference in composition of the pretreatment composition and the imprint resist, together with a non-uniform distribution of the pretreatment composition and the imprint resist may cause non-uniform etching across the field, resulting in poor critical dimension uniformity or incomplete etching.